Static annunciator



2 Sheets-Sheet N LL Ll. N

INVENTORS ATTORNEY Willord A. Derr ond Edward J.Chom.

W. A. DERR ET AL STATIC ANNUNCIATOR April 29, 1958 Filed March 9, 1956 Apri129, 195s uv. A. DERR ErAL 2,832,948

STATIC ANNUNCIATOR United States Patent C STATIC ANNUNCIATOR Willard A. Derr, Pittsburgh, and Edward J. Cham, Penn Township, Westmoreland County, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 9, 1956, Serial No. 570,565

23 Claims. (Cl. 340-213) Our invention relates in general to signal systems, and has reference in particular to an annunciator using static decision elements.

Generally stated, it is an object of our invention to provide a static annunciator that is simple and inexpensive to manufacture and is reliable in operation.

' More specifically, it is an object of our invention lto provide in an annunciator for usinghigh speed static decision elements, sothat closing of an alarm contact for even a moment will result in satisfactory operation of the annunciator.

It is also an object of our invention to provide in an annunciator for using magnetic amplifier decision elements to provide a continuous alarm for even a momentary operation of an alarm Contact.

Another object of our invention is to provide in an annunciator for using a magnetic Flip-Flop decision element for turning on an alarm in response to operation of an alarm contact.

Yet another object of our invention is to provide in an annunciator for using a magnetic amplifier element which is started by operation ot an alarm contact to operate an alarm, and is stopped by operation of a reset switch for turning the alarm ofi.

It is also an object of our invention to provide for using static logic decision Flip-Flop, Not-And and Or elements to provide a reliable annunciator.

Other objects will, in part, be obvious and will, in part, be explained hereinafter.

In practicing our invention in accordance with one of its embodiments a Flip-Flop element is used to turn on an alarm lamp and also apply a signal through an And-Not circuit to turn on an alarm in response to even momentary operation of an alarm contact. A reset switch operated by an attendant turns another Flip-Flop on and applies a signal to the Not terminal of the And-Not element to turn the alarm ofi. Another reset switch is operable to apply a signal to the first Flip-Flop to turn it oit and extinguish the lamp.

As used herein, a Flip-Flop or memory circuit is a circuit element which provides an output signal in response to a first condition, which output signal continues even though said first condition ceases to exist, and terminates said output signal in response to a second condition other than cessation of said first condition.

An And-Not circuit is a circuit element which4 provides an output signal in response to one input signal, but only in the event that a second input signal is absent.

An Or circuit element is a circuit which provides an output signal in response to any one of a number of input signals.

For a more complete understanding of the nature and scope of our invention, reference may be made to the following detailed description which may be read in connection with the accompanying drawings, in which:

Figure 1 is a symbolic schematic circuit of lan annunciator embodying the invention in one of its forms, and

Figs. 2A and 2B taken together are a schematic diagram of the symbolic circuit shown in Fig. 1.

Referring to Fig. 1 the reference numberal 10 denotes generally an annunciator having an alarm AL, which may give an audible sound, and a plurality of alarm lamps or indicators represented by lamps L1 and L2. Operation of the alarm AL is effected through operation of a signal initiating device or alarm Contact ALIV which applies an input signal to a Flip-Flop element FFI to place said Flip-Flop in the on condition. An output signal is thereupon -applied to light the signal lamp LI, through an amplifier A1. At the same time the output signal-is v Flip-Flop FFI is also applied to the hold terminal of they Flip-Flop ZFFI.

Since the alarm reset switch AR is normally open, the Flip-Flop 2FFI will normally have no output signal, so that application of a signal to the And terminal of the 1 And-Not circuit ANI will immediately result in an output signal. This Vsignal is applied to the Or circuit ORl and thence to the alarm AL through an amplifier 2A. The lamp LI and the alarm AL are therefore energized. The alarm may be turnedofl by operating the alarm reset switch AR which turns the Flip-Flop FFlon and applies a signal to the Not terminal of the And-Not element ANI, terminating its output. VThe lamp LI may be turned 0E by the attendant operating a lamp reset switch LR which applies a signal to the ofi terminal of the Flip- Flop FFI; This terminates the output signal to the lamp LI and extinguishes it, but only if the alarm contact ALI is open. At the same time the output signal is removed from the And terminal of the And-Not circuit and from the hold terminal of the Flip-Flop ZFFI.

Other alarm contacts may be used with the annunciator, being represented by an alarm contact ALZ, which is connected to the input or on terminal of an associated Flip- Flop element FF2` for operating the lamp L2 through `an amplifier A2. A Flip-Flop element ZFFZ and an And- Not element AN2 are associated with the Flip-Flop FFZ in the manner described hereinbefore for Flip-Flop FFI, for likewise applying a signal to the Or circuit ORI in the event of operation of the alarm contact ALZ.

Referring to Figs. 2A and 2B, it will be seen that the Flip-Flop elements FFI and FFZ, which are substantially identical, may be of a type described in detail in a copending application Serial No. 511,506 of Robert A. Rainey and William G. Hall, filed May 27, 1955, and now Patent No. 2,792,564, and may comprise a plurality of magnetic cores 11 and I2 having thereon gating or output windings 13 and I4, and reset or control windings I5 and 16 respectively. The gating or output windings 13 and 14 are energized from the secondary winding I7 of a transformer I8, being connected to opposite terminals thereof, and through rectifier devices 19 and 20 back to a center tap 22 ofthe secondary Vwinding through an output resistor 24.

The rectifier devices I9 and 20 are so arranged in circuit With the gating windings 13 and 14 as to produce magnetic ux to provide fof positive saturation of the cores 1I and I2. The reset -or control windings I5 and 16 are connected to a secondary winding 26 of the transformer 18 in connection with rectifier devices 28 and 29 for electinga 'flow of areset current through these windv Patented Apr. 29, s

When the transformer 18 is energized, the windings 13 and 14 will be alternately energized on successive half cycles for producing positive saturation of the cores 11 and 12. The windings` and 16 are likewise energized, and -they are arranged to drivethe coreseto negative saturation on the half cycles following those in which positive saturation is effected. Under these conditions, substantially all the voltage of the winding 17 appears across the output windings 13 and 14, and substantially no voltage is available at the output or load resistor 24; Application of a voltage signal to the onterminal 37 blocks the flow of current through the reset windings 15 and 16 at terminal 38 and thus prevents reset. Accordingly, since the cores 11 and 12 are driven to positive saturation by the windings 13 and 14, on the following half cycles the impedance of the windings 13 and 14 will be relatively low, and substantially all the voltage of the transformer 17 on succeeding half cycles will appear at the load resistor 24 so as to provide an output signal at the output terminal 40. Thus, the reset circuit controls the gate or output circuit in response to the presence or absence of' blocking signals originating externally of the reset circuit. In this manner the reset winding also functions as a control winding. Similarly, the reset circuit functions as a control circuit. A feed-back circuit including a rectifier device 41 connects the output terminal to the reset or control circuit and provides fora continued blocking of the reset current even though the input signal be removed by opening of the alarm contact ALi. A memory circuit comprising resistors 43 and 44 connected to -the windings 13 and 14 is connected by a conductor 45 to the reset circuit to provide for more positive continuation of the reset blocking signal, so that the Flip-Flop will continue in 4the on condition for an extremely long interval of time, `once a signal has been applied to the on terminal 37 even momentarily.

Termination `of the output signal from the Flip-Flop is effected by applying a signal to an off terminal 47 which is connected through a rectifier device 48 to a center tap 49 of the secondary winding 26 for overcoming the effect of the reset blocking signal to produce negative saturation of the cores 11 and 12 and prevent gating an output from the windings 13 and 14.

The output voltage from the terminal 40 of the Flip- Flop FP1 is applied to the amplifier A1 which comprises a pair of cores 50 and 51 of magnetic material having input windings 52 and 53 thereon :together with output windings 55 and 56, respectively. The output windings 55 and 56 are connected in circuit with rectifier devices 58 and 59 and the secondary windingr60 of a transformer 62, for applying voltage therefrom to a bridge circuit 64 of rectifier devices 65. The lamp L1 is connected to the output circuit of the bridge circuit 64. Accordingly, with no signal applied to the input windings 52 and 53 the load on output windings 55 and 56 presents a relatively high irnpedance to alternating current from the secondary winding 60, so that the lamp L1 Vwill be deenergized. The application of a direct current signal from the Flip-Flop FFI to the input windings 52 and 53 produces saturation of the cores 50 and 51, thus reducing the impedance of the windings 55 and 56 to effect energization of the lamp L1 from a transformer 62.

The Flip-Flop element 2FF1 is of a type having an on terminal and a hold terminal 71, both of which must be energized to obtain an output from the terminal 7,2, and

this output continues even though the -on terminal is deenergized until the hold terminal is deenergized. One form -of such an element is described in detail in the copending application Serial No.VV 517,790,V of1 Robert I. Van Nice, filed Ju'ne 24, 1955, andnow Patent No. 2,760,085. As therein "described, the Flip-Flop ZFFI comprises a pair Vof cores 74 and 7 5 of magnetic material having gatingfor output windings 76 and'77 which are energized from a secondary winding 79 of a transformer..

8), and are connected to the output terminal 72 through rectifier devices 81 'and 82 in comjunction with a non-linear impedance 84 comprising a rectifier device 85, a resistor 86 and a direct current source 87, such as a battery. Reset or control windings 90 and 91 are provided on the cores 74 and 75, and are connected to a secondary winding 92 of the transformer 80 in circuit with rectifier devices 93 and 94 and a non-linear impedance comprising resistors 96 and 97 and rectifier devices 98 and 99 in conjunction with the 'battery 87. A feed-back circuit comprising rectifier device 100 connects the gating windings 76 and 77 to the reset windings 90 and 9,1 for preventing reset. Likewise, memory circuits comprising resistors 101 and 102 are utilized to connect the gating windings 76 and 77 to the reset or control circuit through conductor 193 for insuring continued operation after gating is initiated.

With the transformer energized, the gating windings 76 and 77 will be energized on Aalternate half Vcycles to produce positive saturation of the cores 74 and 75. On successive half cycles following such positive saturation the reset windings and 91 are energized from the secondary winding 92 to produce negative saturation of the cores so that all of the voltage of the secondary winding 79 appears across the gating windings 76 and 77. rPhe application of a voltage to the on terminal 70 does not prevent reset of the flux in the cores 74 and 75, as was the case with the Flip-Flop FP1, since an alternate reset path is provided through conductor 105. The application of voltages to both the on terminal 70 and lthe hold terminal 71 will block both paths for the reset current and result in an output voltage from the gating windings 76 and 77 at the output terminal 72.

The And-Not element ANI comprises a magnetic core having a gating or output Winding 111 thereon connected to the secondary winding 112 of a transformer 114 through a rectifier device 115 for producing positive saturation of the core 110. The core is also provided with reset or con-trol windings 116 and 117. The reset winding 116 is connected in circuit with a secondary winding 118 of the transformer 114 through a rectifier device 120V and a non-linear impedance comprisinga resistor 121, a battery 122, and a rectifier device 123. The reset winding 117 is connected to a Not terminal 125 in circuit with a rectifier device 126 for effecting negative saturation of the core 110 in response to the application of a voltage to the terminal 125. An And terminal 127 is connected through a rectifier device 128 to the non-linear impedance at point 129 for blocking the ow of reset current through the winding 116 from the secondary winding of the transformer 118.

With the transformer 114 energized, the gating winding 111 will be energized on alternate halt' cycles to produce positive saturation of the core 110. The reset winding 116 will be energized ou successive half cycles following positive saturation to produce negative saturation of the core 19 and thus effect reset. Accordingly, all the voltage of the winding 112 will appear across the gating winding 111, `and no effective output voltage will appear at thc output terminal 130. Should a voltage be applied to the And terminal 127, the flow of reset current will be blocked at point 129, and accordingly gating will result, with the voltage ofthe secondary winding 112 appearing across the output or load resistor 131. This applies a voltage to thc Or circuit ORI through rectifier device 132, causing amplifier 2A to energize the `alarm AL. There is one rectifier or asymmetrically conducting device 132 in each of a plurality of the individual output circuits from the individual static circuit elements, and this has the advantage of blocking any fiow of current from one output into another, even though the plurality of individual output circuits are connected to acommon 'alarm or indicating circuit without interposing any movable elements such as the movable contact arm of a relay. The application of a signal to the Not terminal by operation of the alarm reset switch AR which turns the Flip-Flop 2FF1 on and applies an output signal tothe Not terminal 125, produces negative saturation of the core 110, and it resets the core so that the voltage of the windings 12 again appear acrossthe gating winding 111. This turns the alarm AL oit. v

Operation of lamp reset switch LR applies a signal to the ofI" terminal 47 which turns Flip-Flop PF1 olf and deenergizes lamp L1 providing the alarm contact ALI is open. f

While We have used specific static decision circuits of the magnetic core type for the Flip-Flop, And-Not and Or elements, and we believe that there are important advantages in the use of these elements in the combinations disclosed, it is also apparent that, in the broader aspects of the invention, modified circuits for the decision elements of the magnetic core type may be used, and static decision elements other than of the magnetic core type may also be used to obtain some of the advantages of the invention. Y f

The use of static elements as disclosed herein provides quick responsiveness, durability and reliability to a degree not found in other devices. For example, other devices which employ moving parts, such as relays having movable contacts, require a longer signal and more time to respond thereto, and they are subject to erratic responsiveness or failure because of ifouling, pitting, and other wear on these moving parts.

From the `above description and the accompanying drawings it will be apparent that we have provided in a simple and etective manner for controlling the operation of a common or audible alarm and an individual alarm lamp or other indicator so `as to provide a continuous signal for even momentary operation dior any one of several alarm contacts. A single independent means has been provided for turning oit or silencing the common or audible alarm regardless of the position of any individual alarm contact which has been actuated in thevpast, but without preventing operation of the common or audible alarm if any additional individual alarm contact should be actuated. Also, common means has been provided to restore any individual or visual signals or indicators to their non-alarm condition providing the corresponding individual alarm'contacts are not actuated.

Since an annunciator embodying the features of our invention comprises static decision elements which have nomovingparts, such an Iannunciator is extremely reliable in operation and requires substantially no maintenance. only one cycle provides a continuous alarm which may be readily reset by the operator.

Since certain ychanges may be made in the abovedescribed construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the above description and shown in the accompanying drawings should be `considered as illustrative and not in a limiting sense.

We claim as our invention:

l. An annunciator comprising, an alarm, means connecting the alarm'to a source of electrical energy including a static Or circuit, a plurality of static Flip-Flop elements each having two inputs and one output, means for applying a diiferent signal to one of the inputs of each of a plurality of the static Flip-Flop elements, means connecting the output Vof each of a plurality of the static Flip-Flop elements to apply a signal to the Or circuit, and means including a reset device connected to apply a signal to at least one static Flip-Flop element to remove the output signal from the Or circuit.

2. In an annunciator, a'plurality of signal devices, means including a plurality of static Flip-Flop memoryy circuits each connected to apply an output signal to one signal device, signal device operating means connected to apply individual input signals to the static Flip-Flop circuits to produce the output signal, and means including a Even momentary operation of the contacts for reset device connected to apply an additional input signal to one or more of the static Flip-Flop circuits to terminate the output therefrom.

3. An annunciator comprising, a `signal device, an indicator, a Flip-lop connected to eiect energization of the signal device and indicator, means applying an input signal to the Flip-Flop to produce an output signal, means including an additional Flip-Flop operable to interrupt" the output signal to the signal device, and reset means applying signals to the Flip-Flops to terminate the signals to the indicator and signal device. l

4. ln an annunciator, a common signal device for a plurality of circuits, an Or element having an output circuit connected to effect operation of the signal device and having a plurality of input circuits, a plurality of indicators individual to each circuit, a Flip-Flop element individual to each indicator having an output circuit for etectin'g energization of its indicator and one of the input circuits to the Or element, alarm means individual to each Flip-Flop element connected to apply an input signal thereto to produce an output signal, means including an additional Flip-Flop element for each said Flip- Flop to terminate the output signal to the Or from said Flip-Flop, and a reset switch common to said additional Flip-Flops for applying a reset signal thereto.

5. In an annunciator, an alarm, a static Or element having an output circuit connected to effect operation of the alarm and having a plurality of input circuits, a lamp individual to each input circuit, a static Flip-Flop element having on and on input circuits and an output circuit connected to effect energization of each lamp and its Or input circuit, an alarm switch for applying a signal to the on circuit of the Flip-Flop element to produce an output, a static And-Not circuit connected between the Flip-Flop and the associated Or input circuit with the And terminal in said circuit, an additional static Flip- Flop element having a hold input circuit energized from the first Flip-Flop and having an on input circuit, said additional Flip-Flop element having an output circuit connected to the Not circuit of the And-Not circuit, and reset switches connected to apply reset signals to the otr and on terminals of the Flip-Flop and additional Flip- Flop, respectively.

6. An annunciator comprising, an alarm, static means responsive to any one of a plurality of signals for energizing the alarm in response to any one of a plurality of signals, other means applying a signal to said static means in response to the existence of one signal and the absence of another signal, an alarm initiating device, a lamp, further static means responsive to operation of the alarm initiating device to apply a signal to the lamp and to the static means responsive to the existence of one signal, a reset device, means responsive to operation of the reset device and existence of the signal from the further means to apply a signal to the other means to terminate the absence of said another signal.

7.- In an annunciator, an alarm, a decision element having a magnetic core, with a gating winding connected toV eiect energization of the alarm and having a plurality of reset windings with input terminals to which application of a ,signal respectively blocks and eects reset to produce an output and block an output, a lamp, another decision element having a magnetic core with an output winding connected to apply an output signal to the lamp and to one input terminal of said rst-mentioned decision element, said another decision element having a pair of reset windings with input terminals to which the application of a signal respectively produces and terminates an output from the output winding of said another decision element, an alarm switch connected to apply a signal to the terminal for producing an output from said another decision element, a vreset switch connected to apply a signal to the terminal to terminate output from said another element, yet another decision element having a magnetic core with an output winding connected to apply a signal to the reset terminal ,of said first mentioned decision element and having a plurality of reset windings both of which must be energized to produce an output from theoutput winding and one of which deenergization thereof terminates said output, circuit means connecting said one reset winding to the output Winding of said another decision element, and another reset switch connected to apply a signal to` the other reset winding of said yet another decision element.

8. in an annunciator, -a signal device common to a plurality of signal circuits, a static Or element having an output circuit connected to effect energization ofthe signal device and having a plurality of input circuits, an indicator individual to each lsignal circuit, a static Flip- Flop element individual to each signal circuit, circuit means connecting the indicator to its associated Flip- Flop element, means operable to connect each signal circuit to its associated `Flip-Flop element to turn said element on, reset means including an additional static Flip- Flop element individual to each signal circuit connecting the other Flip-Flop element individual to the same signal circuit to a different one of the said plurality of input circuits of the Or element operable to turn the common signal device oiiE independently of the condition of the signal circuit means, and additional resetmeans common to said other Flip-Flop elements operable to turn the individual indicator off, provided that the individual signal circuit means is not operated.

9. An annunciator comprising, a common signal device, a static Or element havingan output circuit connected to eilect energization of thecomrnon signal device, and having a plurality of input circuits, a plurality of indicators each individual to a particular signal circuit, a static Flip-Flop circuit elenientindividual to each signal circuit and connected to effect energization of the indicator individual to such circuit, means individual to each` signal circuit to apply a signal to the associated Flip-Flop element to turn it on, reset Vmeans including an additional Flip-Flop element and au And-Not element individual to each signal circuit, said And-Not element 'being connected in circuit between the output circuit of the first mentioned Flip-Flop and an inputfcircuit of the Or element, torti-ansmit a signal from the rst mentioned Flip-Flop element to the Or element unless the additional Flip-Flop element is turned on, a common reset switch operable to apply a signal to turn the additional Flip-Flop elements on, and additional reset switch means operable to apply a signal to the tirst mentioned `Flip-Flop elements to turn them off only if the signal from the signal circuit means is terminated.

10. In an annunciator, a plurality of indicators, a cir'- cuit individual to each of a plurality of the indicators, said individual circuits consisting of static elements and each having an output connected to one of the indicators, said individual circuits of static elements each having a plurality of inputs and causing a change in the electrical condition of its output to its indicator upon a change ,in the, electrical condition at one input and said change in the output remaining until there is a change in the electrical condition at another input, a common reset circuit connected to said other input of each of a plurality of the individual circuits of static elements and being operable to end said change in the output of those of the individual circuits of static elements where there Was 'a change in output at least if the change in the electrical condition at the iirst said input of the individual circuit ofstatic elements has ended.

1l. In an annunciator, a plurality of signal initiating devices, circuitv means consisting of static elements connected to said .signal initiating devices, a plurality of outputs -from said circuit means consisting of static elements with each output responsive to the operation of one of said signal initiating devices, a common. alarm circuit conccted toa plurality` of said output circuits, and an asyml 8 rnetrically conducting device in each of a plurality of said output circuits to block liow of current from one output circuit into another output circuit.

12. In an annunciator, a plurality of signal initiating devices, circuit means consisting of static elements connected to saidisignal initiating devices, a plurality of outputs from said "circuit means consisting of static elements with each output responsive to the operation of one of said signal initiating devices, a plurality of indicators each responsive to one of the outputs from the circuit means consisting of static elements, means for resetting those indicators which have responded to their respective signal initi'atiugdevices if an indication is no longer called for, a common alarm circuit 4connected to a plurality of said output circuits, an asymmetrically conducting device in each of a plurality of said output circuits to block iiow of current from one output circuit into another output circuit, andan alarm reset circuit for turning ofi the alarm without preventing its operation if one of the signal initiating devices is actuated after the alarm is turned ott by the reset circuit.

13. In an annunciator, a plurality of indicators, a circuit individual Vto each of a plurality of the indicators, said individual circuits consisting of static elements and each having an output connected to one of the indicators, said individual circuits of static elements each having a plurality of inputs and causing a change in the electrical condition of its output to its indicator upon a change in the electrical condition 'at one input and said change in the output remaining until there is a change in the electrical conditioniat another input, a common indicator reset circuit connected to said other input of each of a plurality of the individual circuits of static elements and being operable to end said change in the output of those of the indivi-dual circuits of static elements where there was a change in output at least if the change in the electrical condition at the rst said input of the individual circuit of static elements has ended, a common alarm circuit connected to a plurality of the outputs of said individual circuits of static devices, vand "an asymmetrically conducting device in each of a plurality of the connections to said common'alarm circuit.

14. In an annunciator, a plurality of indicators, a circuit individual to each of a plurality of the indicators, each of said individual circuits including a memory circuit of static elements and each having a plurality of inputs and at least one output, means connecting an output of each of a ,plurality of the individual circuits to a different one of the plurality of indicators, means for making a separate connection to each of one ot' the inputs of each individual circuit, and a common reset circuit connected to a plurality of other inputs of the individual circuits.

15. In an annunciator, a plurality of indicators, a circuit individual to each of a plurality of the indicators, each of said individual circuits including a memory circuit of static elements and each having a plurality of inputs and at least one output, means connecting an output of each of a plurality of the individual lcircuits to a different one of the plurality of indicators, means for making a separate connection to each of one of the inputs of each individual circuit, a common reset circuit connected to a plurality of other inputs of the individual circuits, a common alarm Vcircuit connected to a plurality of said individual circuits, and an asymmetrically conductingdevice in each of a plurality of the connections of the individual circuits to the common alarm circuit.

16. In an annunciator, a plurality of indicators, a circuit individual to each of a plurality ofthe indicators, each of said individual circuits including a memory circuit of static elements and each having a plurality vof inputs and at leastone output, means connecting an output ofeach of a plurality of the( individual circuits to a different one olf-,the plurality of indicators, means for making a separute connection to each of one of the inputs of each individual circuit, a common reset circuit connected to a plurality of other inputs of the individual circuits, a common alarm circuit connected to a plurality of said individual circuits, an asymmetrically conducting device in each of a plurality of the connections of the individual circuits to the common alarm circuit, one or more additional memory circuits of static elements connected to the alarm circuit to eiect the energization thereof, and an alarm reset circuit connected to said one or more additional memory circuits of static elements for causing deenergization of the alarm.

17. In an annunciator, a plurality of signal devices, means including a plurality of static Flip-Flop memory circuits each connected to apply an output signal to one signal device, signal device operating means connected to apply individual input signals to the static Flip-Flop circuits to produce the output signal, and means including a reset device connected to apply an additional input signal to one or more of the static Flip-Flop circuits to terminate the output therefrom, said Flip-Flop memory circuits each including saturable core means having control circuit means and output circuit means inductively coupled thereto, said saturable core means operable to cause said output circuit means to provide said output signal in response to the application of said input signal to said control circuit means and to cause said output circuit means to terminate said output signal in response to the application of said input signal to-said control circuit means.

18. In an annunciator, a plurality of signal initiating devices, circuit means consisting of static elements connected to said signal initiating devices, a plurality of outputs from said circuit means consisting of static elements with each output responsive to the operation of one of said signal initiating devices, a plurality of indicators each operable to be energized in response to a change in the output of one of said static elements, means including a manually operable device connected to a plurality of said static elements for changing the energization of such of those indicators as have responded to their corresponding signal initiating devices, a common alarm circuit connected to a plurality of said output circuits, and an asymmetrically conducting device in each of a plurality of said output circuits to block flow of current from one output circuit into another output circuit.

19. ln an annunciator, a plurality of signal initiating devices, circuit means consisting of static elements connected to said signal initiating devices, a plurality of outputs from said circuit means consisting of static elements with each output responsive to the operation of one of said signal initiating devices, a plurality of indicators each connected to a different one of said outputs from the static elements, a common alarm circuit connected to a plurality of said output circuits, an alarm reset circuit connected to the static elements for turning off the alarm without preventing its operation if one of the signal initiating devices is actuated after the alarm is turned oif by the reset circuit, and an asymmetrically conducting device in each of a plurality of said output circuits to block flow of current from one output circuit into another output circuit.

20. In an annunciator, a plurality of signal initiating devices, circuit means consisting of static elements connected to said signal initiating devices, a plurality of outputs from said circuit means consisting of static elements with each output responsive to the operation of one of said signal initiating devices, a plurality of indicators each connected to one of said outputs to be energized in response to the operation of the corresponding one of said signal initiating devices, a common alarm circuit connected to a plurality of said output circuits of the static elements to be energized thereby in response to the operation of any one of the said signal initiating devices, means including manually operable means connected to 10 the static elements for changing the energization of the alarm and such of those indicators as have responded to the operation of one or more signal initiating devices, and an asymmetrically conducting device n'each of a plurality of said output circuits to block flow of current from one output circuit into another output circuit.

2l. In an annunciator, a plurality of indicators, a circuit individual to each of a plurality of the indicators, said individual circuits consistingof static elements and each having an output connected to one ofthe indicators, said static elements each including saturable core means having control circuit means and output circuit means inductively coupled thereto, said output circuit means of some of said static elements connected to alect the control circuit means of other of said static elements, each said output connected to one of the indicators including an output circuit means of one of said static elements, said individual circuits of static elements each having a plurality of inputs and causing a change in the electrical condition of its output to its indicator upon a change in the-electrical condition at one input and said change in the output remaining until there is a change in the electrical condition at another input, a common indicator reset circuit connected to said other input of each of a plurality of the individual circuits of static elements and being operable to end said change in the output of those of the individual circuits of static elements Where there was a change in output at least if the change in the electrical condition at the first said input of the individual circuit of static elements has ended, a common alarm circuit connected to a plurality of the outputs of said individual circuits of static devices, and an asymmetrically conducting device in each of a plurality of the connections to said common alarm circuit.

22. In an annunciator, a plurality of indicators, a circuit individual to each of a plurality of the indicators, each of said individual circuits including a memory circuit of static elements and each having a plurality of inputs and at least one output, said memory circuit of static elements including control and output circuit means inductively coupled to saturable core means and having feedback means connecting said output circuit means to said input circuit means, means connecting an output of each of a plurality of the individual circuits to a dierent one of the plurality of indicators, means for making a separate connection to each of one of the inputs of each individual circuit, and a common reset circuit connected to a plurality of other inputs of the individual circuits.

23. In an annunciator, a plurality of indicators, a circuit individual to each of a plurality of the indicators, each of said individual circuits including a memory circuit of static elements and each having a plurality of inputs and at least one output, said memory circuit of static elements including control and output circuit means inductively coupled to saturable core means and having feedback means connecting said output circuit means to said input circuit means, means connecting an output of each of a plurality of the individual circuits to a different one of the plurality of indicators, means for making a separate connection to each of one of the inputs of each individual circuit, a common reset circuit connected to a plurality of other inputs of the individual circuits, a common alarm circuit connected to a plurality of said individual circuits, and an asymmetrically conducting device in each of a plurality of the connections of the individual circuits to the common alarm circuit.

References Cited in the file of this patent UNITED STATES PATENTS 2,707,777 Marmorstone May 3,1955 2,709,250 Marmorstone May 24, 1955 2,745,090 Grillo May 8, 1956 2,769,971 Bashe Nov. 6, 1956 

